library: cover every credited artist in plays, downloads and menus

Credit all album artists in play aggregation and recorded plays, include the
relation rows in the downloaded artist list, and fall back to the album artist
display name in download groups.

Also keep the chooser scrollable, close it when the track changes, keep the
singular id in the album-artist label, stop a nested artists container from
swallowing later artist elements, and make the refs encoding length-prefixed
so tag values cannot corrupt it.

app/src/test/kotlin/com/subtracks/data/model/ArtistRefsCodecTest.kt

@@ -0,0 +1,25 @@
+package com.subtracks.data.model
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class ArtistRefsCodecTest {
+    @Test
+    fun roundTripsNamesWithTheOldSeparatorsAndColons() {
+        val refs =
+            listOf(
+                ArtistRef("ar1", "Name\u001Ewith\u001Fseparators"),
+                ArtistRef("ar:2", "1:Colon Artist"),
+                ArtistRef("", ""),
+            )
+
+        assertEquals(refs, ArtistRefsCodec.decode(ArtistRefsCodec.encode(refs)))
+    }
+
+    @Test
+    fun decodesEmptyAndMalformedValuesAsEmpty() {
+        assertEquals(emptyList<ArtistRef>(), ArtistRefsCodec.decode(""))
+        assertEquals(emptyList<ArtistRef>(), ArtistRefsCodec.decode("not a ref"))
+        assertEquals(emptyList<ArtistRef>(), ArtistRefsCodec.decode("9:short4:name"))
+    }
+}

app/src/test/kotlin/com/subtracks/data/source/subsonic/SubsonicXmlTest.kt

@@ -191,6 +191,27 @@ class SubsonicXmlTest {
         )
     }
 
+    @Test
+    fun ignoresNestedArtistsOutsideTheArtistsContainer() {
+        val songs =
+            songs(
+                """
+                <subsonic-response status="ok">
+                  <song id="s1" title="Collab" albumId="al1">
+                    <artists>
+                      <artist id="ar1" name="A"/>
+                    </artists>
+                    <contributors>
+                      <artist id="ar9" role="composer"/>
+                    </contributors>
+                  </song>
+                </subsonic-response>
+                """.trimIndent(),
+            )
+
+        assertEquals(listOf(ArtistRef("ar1", "A")), songs.single().artists)
+    }
+
     @Test
     fun mapsNestedSongArtistRefs() {
         val songs =
@@ -205,6 +226,9 @@ class SubsonicXmlTest {
                     <albumArtists>
                       <artist id="ar3" name="Album Artist"/>
                     </albumArtists>
+                    <contributors>
+                      <artist id="ar4" role="composer"/>
+                    </contributors>
                   </song>
                 </subsonic-response>
                 """.trimIndent(),

app/src/test/kotlin/com/subtracks/data/sync/SyncServiceTest.kt

@@ -1045,6 +1045,44 @@ class SyncServiceTest {
             assertEquals(listOf("A", "B"), filtered.map { it.name })
             assertEquals(listOf(1L, 1L), filtered.map { it.albumCount })
             assertEquals(ListDownloadStatus(total = 1, downloaded = 1), db.downloadDao().artistStatus(1, "a2").first())
+            assertEquals(
+                setOf("A", "B"),
+                db
+                    .libraryDao()
+                    .downloadedArtists(1)
+                    .allRows()
+                    .map { it.name }
+                    .toSet(),
+            )
+        }
+
+    @Test
+    fun playsOnASharedAlbumReachEveryAlbumArtist() =
+        runTest {
+            insertSource()
+            val source =
+                FakeMusicSource(
+                    artists = listOf(artist("a1", "A"), artist("a2", "B")),
+                    albums =
+                        listOf(
+                            album("al1").copy(
+                                artistId = "a1",
+                                artists = listOf(ArtistRef("a1", "A"), ArtistRef("a2", "B")),
+                            ),
+                        ),
+                    songs = listOf(song("s1").copy(albumId = "al1", playCount = 3, played = 100)),
+                )
+
+            SyncService(db, source).sync()
+
+            assertEquals(3L, db.libraryDao().artistOnce(1, "a2")!!.playCount)
+            assertEquals(100L, db.libraryDao().artistOnce(1, "a2")!!.played)
+
+            db.libraryDao().recordPlay(1, "s1", 500)
+
+            assertEquals(4L, db.libraryDao().artistOnce(1, "a1")!!.playCount)
+            assertEquals(4L, db.libraryDao().artistOnce(1, "a2")!!.playCount)
+            assertEquals(500L, db.libraryDao().artistOnce(1, "a2")!!.played)
         }
 
     private suspend fun totalChanges(): Long =

app/src/test/kotlin/com/subtracks/ui/components/ArtistChooserSheetTest.kt

@@ -5,6 +5,7 @@ import androidx.compose.ui.test.assertIsDisplayed
 import androidx.compose.ui.test.junit4.v2.createAndroidComposeRule
 import androidx.compose.ui.test.onNodeWithText
 import androidx.compose.ui.test.performClick
+import androidx.compose.ui.test.performScrollTo
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.subtracks.data.model.ArtistRef
 import com.subtracks.ui.theme.SubtracksTheme
@@ -43,4 +44,27 @@ class ArtistChooserSheetTest {
 
         assertEquals(ArtistRef("ar2", "B"), opened)
     }
+
+    @Test
+    fun longListsScrollToTheLastArtist() {
+        var opened: ArtistRef? = null
+        val artists = (1..20).map { ArtistRef("ar$it", "Artist $it") }
+        composeRule.setContent {
+            SubtracksTheme {
+                ArtistChooserSheet(
+                    artists = artists,
+                    onArtistClick = { opened = it },
+                    onDismiss = {},
+                )
+            }
+        }
+
+        composeRule.onNodeWithText("Artist 20").performScrollTo().assertIsDisplayed()
+
+        composeRule.mainClock.autoAdvance = false
+        composeRule.onNodeWithText("Artist 20").performClick()
+        composeRule.mainClock.advanceTimeBy(1_000)
+
+        assertEquals(ArtistRef("ar20", "Artist 20"), opened)
+    }
 }

app/src/test/kotlin/com/subtracks/ui/library/AlbumArtistLabelTest.kt

@@ -0,0 +1,40 @@
+package com.subtracks.ui.library
+
+import com.subtracks.data.model.Album
+import com.subtracks.data.model.ArtistRef
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class AlbumArtistLabelTest {
+    @Test
+    fun creditsBothTheSingularIdAndEveryPluralRef() {
+        val album =
+            album(
+                artistId = "a1",
+                artists = listOf(ArtistRef("a2", "B")),
+            )
+
+        assertTrue(isAlbumArtist(listOf(album), "a1"))
+        assertTrue(isAlbumArtist(listOf(album), "a2"))
+        assertFalse(isAlbumArtist(listOf(album), "a3"))
+    }
+
+    private fun album(
+        artistId: String?,
+        artists: List<ArtistRef>,
+    ) = Album(
+        sourceId = 1,
+        id = "al1",
+        artistId = artistId,
+        name = "Album",
+        albumArtist = "Various Artists",
+        created = 0,
+        coverArt = null,
+        genre = null,
+        year = null,
+        starred = null,
+        songCount = 1,
+        artists = artists,
+    )
+}